The present invention relates to a storage system that is expandable from a small-scale to a large-scale configuration.
Storage systems that save data processed in IT systems have come to play a central role in IT systems due to the penetration of IT systems in business and the expansion of the cooperation of IT systems in business resulting from the development of the Internet. There are numerous types of storage systems ranging from systems of a small-scale configuration to systems of a large-scale configuration.
As one example of a main storage system that provides a small-scale to large-scale configuration, in the prior art, an architecture storage system such as shown in FIG. 36 is disclosed in JP 2000-99281 A. The storage system 8 is disposed with plural channel IF units 11 that execute data transfer with computers 3 (also called “servers” below), plural disk IF units 16 that execute data transfer with hard drives 2, a cache memory unit 14 that temporarily stores data stored in the hard drives 2, and a control memory unit 15 that stores control information relating to the storage system 8 (e.g., information relating to data transfer control in the storage system 8 and management information of data stored in the hard drives 2). The channel IF units 11, the disk IF units 16, and the cache memory unit 14 are connected by an interconnection 41, and the channel IF units 11, the disk IF units 16, and the control memory unit 15 are connected by an interconnection 42. Also, the interconnection 41 and the interconnection 42 are configured by common buses and switches.
In this manner, in the single storage system 8, the cache memory unit 14 and the control memory unit 15 have a configuration that is accessible from all of the channel IF units 11 and the disk IF units 16.
The channel IF units 11 include an interface (host IF) 104 for connecting to the servers 3, a microprocessor 103 that controls input/output with respect to the servers 3, a memory access unit 106 that controls access to the cache memory unit 14, and a memory access unit 107 that controls access to the control memory unit 15. Also, the disk IF units 16 include an interface (disk IF) 105 for connecting to the hard drives 2, a microprocessor 103 that controls input/output with respect to the hard drives 2, a memory access unit 106 that controls access to the cache memory unit 14, and a memory access unit 107 that controls access to the control memory unit 15. The disk IF units 16 also conduct control of RAID.
In the above-described storage system, it has been possible to flexibly change the number of channel IF units 11 and disk IF units 16 because the channel IF units 11 that control data transfer with the servers 3 and the disk IF units 16 that control data transfer with the hard drives 2 are separated and data transfer between the channel IF units 11 and the disk IF units 16 is controlled through the cache memory unit 14 and the control memory unit 15. For this reason, it has been possible for the storage system to have a small-scale to large-scale configuration.
Also, in the prior art disclosed in JP 2000-242434 A, plural disk array devices are connected to plural servers through disk array switches so that the plural disk array devices are managed as a single storage system by system configuration managing means connected to the disk array switches and each disk array device.